1. Field of the Invention
The invention generally relates to a light source device having a high pressure mercury discharge lamp. In particular, the invention can be used, for example, as a light source for a projector.
2. Description of the Related Art
In a light source device for an optical device, such as a liquid crystal projector, a DLP, or the like, a discharge lamp with high radiance (HID lamp) is used. Recently however there has been a demand for a greater amount of mercury to be added to the discharge lamp than in the conventional case in order to make the optical device more radiant. In one such discharge lamp it is necessary to produce a high voltage during start-up by using a starter to subject a discharge space to an insulation breakdown, and thus to start a discharge.
FIG. 19 shows an arrangement of a conventional discharge lamp light source device. In a light source device for an optical device, conventionally a starter (Ui) is used between the electrodes (E1, E2) to which a high voltage is applied. The secondary winding (Si) of the high voltage transformer (T1) of the starter is series connected to the discharge lamp (Li). After starting a discharge, the function of the starter (Ui) is thus no longer necessary. The discharge current supplied to the discharge lamp (Li) must nevertheless flow via the secondary winding (Si) of the high voltage transformer which has a large winding number. To suppress the formation of heat loss in the secondary winding (Si), it is necessary to make the wire diameter of the winding large, resulting in the disadvantage that an increase in the size and weight of the starter (Ui) is inevitable.
As a measure for eliminating this defect, an outside trigger method can be used which is often used for the trigger in a blinking lamp. With this method, besides the first electrode and the second electrode acting as the two main discharge poles, i.e., an arc discharge after starting, there is an auxiliary electrode. Between the auxiliary electrode and the first or second electrode, a high voltage is applied, plasma is produced by a dielectric barrier discharge in the discharge space, and between the first electrode and the second electrode the main discharge is started by means of a voltage applied beforehand (no-load voltage) by means of the plasma.
After starting the discharge in the primary winding and the secondary winding of the high voltage transformer of the starter, no discharge current flows to the discharge lamp. Thus, in the primary and secondary windings of the high voltage transformer of the starter no heat loss forms. Therefore, both an increase in size and an increase in weight of the starter can be avoided.
In a discharge lamp with a large amount of added mercury, the pressure in the discharge lamp is low due to the condensation of the mercury when the discharge lamp is in the cold state. In this case, starting can take place relatively easily. However, the case of a hot discharge lamp, which can occur shortly after turning off the lamp, the pressure in the discharge space is high due to the vaporized mercury. This is disadvantageous in that a hot restart of the lamp is difficult.
The disadvantage of a difficult hot restart for an optical device such as a projector, or the like, is the disadvantage of convenience of use by the user of this device. This disadvantage of difficult restart has furthermore become more and more serious in recent years due to the increase in the amount of mercury added to implement the outside trigger method.
On the other hand, the conventional discharge lamp (Li) and a feed device (Ni) were connected to one another by feed lines (K1, K2). The starter (Ui) for starting the discharge lamp (Li) was located on a side of the feed circuit. The starter (Ui) produced a high voltage. In the case in which the starter (Ui) produces a pulsed high voltage, the feed lines (K1, K2) are exposed to a high voltage within a short time, which created strong noise.
Furthermore, xe2x80x9cdulling distortionxe2x80x9d of the pulsed high voltage is caused by an electrostatic potential which forms between the feed lines (K1, K2), a conductance in the environment, and by the inductance of the feed lines (K1, K2). The increase in the voltage between the electrodes (E1, E2) is therefore reduced. In order to obtain the pulsed voltage necessary for starting the discharge lamp, more energy than necessary must be delivered by the starter (Ui) in the direction of the feed lines (K1, K2). Moreover, the pulse width is broadened by the xe2x80x9cdulling distortionxe2x80x9d of the pulsed high voltage. In this way, the possibility of the formation of an insulation breakdown in an unintended area, such as the insulation coating of the high voltage transformer (T1) of the starter and the feed lines (K1, K2) or the like, is increased. In this way, there is the danger of a reduction in reliability.
On the other hand, in the case of a DC starter which produces a relatively slowly increasing high voltage, the insulation breakdown phenomenon takes place more frequently, and in proportion to the higher the voltage and the longer the voltage application time. In this instance, one disadvantage is the possibility that the formation of an insulation breakdown in an unintended area increases even more.
For conventional inventions and concepts for starting a high pressure discharge lamp using the outside trigger method, reference can be made to, for example, Japanese Utility Model SHO 37-8045. Here an arrangement is disclosed in which there is a coil which produces a magnetic force, and controls in the operation of a starter circuit which produces a high voltage in the auxiliary electrode by a magnetic force.
Furthermore, in the invention described in Japanese patent disclosure document HEI 5-54983, an arrangement is disclosed in which in the discharge lamp, such as in a high pressure mercury lamp or the like, there are auxiliary electrodes (outside electrodes) adjacent to one another with a distance of a few millimeters to one another.
However, in these conventional inventions and concepts, the formation of an insulation breakdown in an unintended area during restart were not considered at all.
An exemplary object of the invention is to eliminate the disadvantages of the prior art. These disadvantages at least are:
an increase in size or an increase in weight of the starter cannot be avoided if heat loss in the windings is to be avoided,
that restart is difficult shortly after turning off and the discharge lamp is hot;
noise concerns;
as a result of capacitive coupling between the feed lines and the conductor in the vicinity of the starter, greater energy than necessary must be delivered in the direction of the feed lines; and
the possibility of the formation of an insulation breakdown in an unintended area increases thus causing a reduction in reliability.
In a first aspect of the invention in a light source device the following components are connected to one another:
a discharge lamp (Ld) in which a pair of main discharge electrodes (E1, E2) are located opposite to the discharge space (12) and moreover an auxiliary electrode (Et) is arranged such that it does not come into contact with the main discharge space (12);
a feed circuit (Bx) for supplying a discharge current to the main discharge electrodes (E1, E2); and
a starter (Ue) which produces a high voltage between one of the electrodes (E1, E2) for the main discharge and the auxiliary electrode (Et),
an object is achieved in that during the interval during which the starter (Ue) produces a high voltage, a high voltage is also applied at least during part of this interval to the main discharge electrodes (E1, E2).
The object is achieved in a second aspect of the invention in that in the above described invention the high voltage which is produced by the starter (Ue) and which is applied at least partially overlapping in time to the main discharge electrodes (E1, E2) is at least 2.5 times as high as the glow discharge voltage of the discharge lamp (Ld).
The object is furthermore achieved in that the discharge lamp (Ld) contains greater than or equal to 0.15 mg mercury per cubic millimeter of volume of the discharge space (12), and that the high voltage which is also applied to the main discharge electrodes (E1, E2) is greater than or equal to 500 V and at least partially overlaps in time with the interval during which the starter (Ue) produces the high voltage.
The object is moreover achieved in that the high voltage which is also applied to the main discharge electrodes (E1, E2) is pulse-like and at least partially overlaps in time with the interval during which the starter (Ue) produces the high voltage.
The object is moreover achieved in that when a discharge is produced within the discharge space (12) by the high voltage of the starter (Ue), the high voltage which is applied to the main discharge electrodes (E1, E2) is produced by the electrode which is located on the side on which the starter (Ue) is not connected.
The object is moreover achieved in that a high voltage generating part (Ub) which comprises at least one high voltage transformer (Te) of a starter circuit is separated from the feed circuit part (By).
In the outside trigger method the starting property cannot be enhanced simply by increasing only one of the voltages. Specifically the high voltage applied between either the first electrode (E1) or the second electrode (E2) and the auxiliary electrode (Et) and the no-load voltage is needed in order to start the actual main discharge.
It is specifically necessary, according to the time after turning off, i.e., according to the conditions of the discharge lamp at the instant of starting, such as the temperature and the like, to apply the high voltage and no-load voltage in a suitable equilibrium. Moreover, depending on the time lapse after turning off either the high voltage to be applied or the no-load voltage or the two are very high, even if a suitable equilibrium is being maintained, there is the danger of the formation of an insulation breakdown in an unintended area.
With respect to the limit of dielectric resistance which can be imparted to the light source device, the limit being is set with respect to the compactness and economic efficiency which are required of the optical device. There is therefore a minimum time lapse after turning off in which a restart is possible.
With consideration of these circumstances a first aspect of the invention is described first using FIG. 1 and FIG. 2 which relate to tests by the inventors. FIG. 1 shows the result of a test using a discharge lamp which contains 0.15 mg mercury per cubic millimeter of volume of the discharge space and in which the distance between the main discharge electrodes which act as the two poles for the main discharge, i.e., the first electrode and the second electrode, is 1.2 mm.
The test was run, as shown in FIG. 2, such that a DC source (Mx), a feed circuit (Bx) and a starter (Ue) were connected to the lamp (Ld). In order to deliver an independent voltage to the primary winding (Pe) of the high voltage transformer of the starter and to the no-load voltage applied to the main discharge electrodes (E1, E2), a variable voltage source (Vp) and a variable voltage source (Va) were connected. In the state in which the no-load voltage was applied to the discharge lamp (Ld), a high voltage pulse which the starter (Ue) produces was applied between the first electrode (E1) and the auxiliary electrode (Et).
The reason for applying the no-load voltage to the discharge lamp (Ld) as the charging voltage for the capacitor (Ca) via a resistor (Ra) with a high resistance value is as follows:
When the discharge lamp (Ld) is started, the capacitor (Ca) quickly supplies a current. After starting the discharge lamp (Ld), the resistance value of the resistor (Ra) is high. Application takes place therefore to prevent the variable voltage source (Va) from influencing the operation of the feed circuit (Bx).
The peak voltage (Vtrg) of the high voltage pulse of the starter (Ue) was set by setting the variable voltage source (Vp) to 4.4 kV, 8.3 kV, 12.1 kV and 16.1 kV. These values were measured in the state in which the connection of a secondary winding (Se) of the high voltage transformer of the starter to the auxiliary electrode (Et) of the discharge lamp was interrupted. The voltage which formed in the secondary winding (Se) of the high voltage transformer of the starter (Ue) was measured using an oscilloscope.
During operation of the starter (Ue), the discharge lamp (Ld) was operated for four minutes and, at the instant the discharge lamp is turned off was taken as the reference point. After a suitable time interval the discharge lamp (Ld) was operated and the time until successful starting of the lamp (Ld) and accordingly the time (Trst) during which a restart is impossible were measured (y-axis in FIG. 1).
The no-load voltage (Vopn) was measured such that the variable voltage source (Va) was set essentially to 280 V, 350 V, 500 V, 750 V, 1000 V, 1300 V, 1600 V and 1900 V and that the voltage applied to the main discharge electrodes (E1, E2) with actual successful starting of the discharge lamp (Ld) was measured using an oscilloscope (x-axis in FIG. 1).
The following can be taken immediately from FIG. 1:
the more the peak voltage (Vtrg) of the high voltage pulse of the starter (Ue) is increased, and the more the no-load voltage (Vopn) is increased, the more the time (Trst) during which a restart is impossible is shortened.
As was described in the means for achieving an object of the invention, during the time interval which overlaps with the interval during which the starter (Ue) produces a high voltage, a high voltage is applied as a no-load voltage to the main discharge electrodes (E1, E2), the amount of time during which a hot restart is impossible is shortened and the disadvantage that a hot restart is difficult is eliminated.
Preferred embodiments of the invention are described below.
The time during which a restart is impossible is shortened, and the more the no-load voltage is increased, can be physically interpreted as follows:
As was described above, the high voltage of the starter (Ue) is applied to the auxiliary electrode (Et). A plasma is produced in the discharge space by a dielectric barrier discharge. A glow discharge will be produced between the main discharge electrodes (E1, E2) by means of the plasma from the applied no-load voltage. This is a random phenomenon which is dependent on the density of gas atoms present in the discharge space. To produce a glow discharge, a higher no-load voltage is needed, and a higher temperature of the discharge lamp. This increases the probability of the formation of a glow discharge proportional to the increase of the no-load voltage, and the time during which a restart is impossible is shortened.
In a more detailed examination of FIG. 1 it becomes apparent that regardless of the peak voltage (Vtrg) of the high voltage pulse of the starter (Ue), the time during which a restart is impossible in the range up to roughly 500 V is quickly shortened by increasing the no-load voltage. Furthermore, the difference in the time during which a restart is impossible is further reduced. In the case where the no-load voltage is further increased, the time during which a restart is impossible continues to be shortened, but the degree of shortening is reduced. Furthermore, it becomes apparent that in the range of greater than or equal to roughly 1600 V, the time during which a restart is impossible is no longer shortened very much even if the no-load voltage is increased even further.
It is therefore feasible in the case of using this discharge lamp in an actual light source device, a voltage of at least 500 V, preferably of greater than or equal to 600 V, can be applied as a no-load voltage. Furthermore, it is advantageous to keep it at less than or equal to 1600 V in order to prevent the increased danger of insulation breakdown in an unintended area.
Even if by applying the high voltage of the starter (Ue) a glow discharge is successfully produced, for its transition into an arc discharge it is necessary to supply a discharge plasma with energy sufficient to achieve continued formation of a thermionic emission of the electrodes. According to the increase of the no-load voltage, the reliability of starting a discharge of the discharge lamp increases. It can be imagined that the reason for this is the following:
In contrast to the case of a glow discharge, the energy for a thermionic emission is dependent on the density of the gas atoms present in the discharge space. It can therefore be imagined that saturation begins occurring at 500 V.
Hence it follows that the curves in FIG. 1, which are shown using groups of plot data, were formed by the fact that for one plot, for which producing the glow discharge during the time during which a restart is impossible is shortened, is proportional to the increase of the no-load voltage, and for other plot, for which for the transition into an arc discharge the time at which a restart is impossible is shorted, is proportional to the increase of the no-load voltage which is saturated at a voltage of 500 V, have been superimposed.
The plot for which for the transition into an arc discharge the time during which a restart is impossible is shortened being proportional to the increase of the no-load voltage depends on how much wattage can be delivered in addition in the successful formation of a glow discharge for the transition into the arc discharge. This phenomenon therefore depends on the glow discharge voltage of the discharge lamp.
A typical glow discharge voltage used in the test shown in FIG. 1 is 180 V to 220 V. Using an average of approximately 200 V, and in conjunction with the voltage of 500 V, for which the sudden shortening tendency of the time for which a restart is possible decreases, it is feasible to apply as the no-load voltage a voltage which is at least 2.5 times, preferably three times, as high as the typical glow discharge voltage of the discharge lamp.
In conjunction with the voltage of 1600 V, for which the time during which a restart is impossible is hardly shortened any further, it is advantageous to keep the voltage at less than or equal to 8 times as high as the typical glow discharge voltage of the discharge lamp in order to prevent the increased danger of insulation breakdown in an unintended area.
Based on one such guideline it is necessary in the design a feed device for the light source device for a certain experimental discharge lamp to determine the typical glow discharge voltage (Vg) of the experimental discharge lamp through testing. In this case, an experimental DC voltage source which has a voltage (Vs) roughly five times as high as the arc discharge voltage during steady-state operation of the experimental discharge lamp, i.e. its nominal voltage, and a current limiter resistor which is approximated as follows:
The nominal wattage during steady-state operation of this experimental discharge lamp is divided by the nominal voltage, from which the nominal current is determined. The voltage (Vs) of the experimental DC voltage source is divided by the nominal current. The current limiter resistor is roughly equal to this value.
Furthermore, the experimental discharge lamp and the current limiter resistor are connected in series to one another and the experimental DC voltage source is connected thereto. The voltage between the electrodes for the main discharge of the experimental discharge lamp, i.e. the lamp voltage (VL), during starting by operation of the starter (Ue) can be determined using an oscilloscope.
FIG. 18 shows an illustration of the waveform of the lamp voltage (VL) during starting. At time ti the starter is operated. It is shown that the lamp voltage (VL) before operation of the starter is equal to the voltage (Vs) of the experimental DC voltage source. However, the voltage quickly drops after operation of the starter, to a flat voltage for a short time interval (Ag) and that afterwards the voltage continues to drop rapidly until it passes into an arc discharge area (Aa).
In the time interval (Ag) a glow discharge forms. By measuring the voltage at this instant, the typical glow discharge voltage (Vg) for the experimental discharge lamp can be determined. The length of the time interval (Ag) of the glow discharge differs depending on the lamp structure, the electrode material, the composition of the contents, or the like, and is normally in the range of a few microseconds to a few dozen milliseconds.
The observed waveform of an actual lamp voltage (VL) during starting however changes depending on the state of the discharge lamp. For example, the observed waveform can depend on the duration of the immediately preceding operation, the time lapse after turning off, the adhesion state of the mercury to the electrodes, and the like. Furthermore, there are also cases in which an arc discharge forms first due to the presence of the mercury and in which the glow discharge cannot be clearly observed, especially when mercury is adhering to the cathode.
It is therefore advantageous to carry out the observation in the state in which no mercury is adhering to the cathode, and after natural air cooling of, for example, after roughly 20 minutes. The state in which no mercury is adhering to the cathode is obtained such that the experimental discharge lamp is operated for roughly five minutes, the mercury is thus completely vaporized and that the lamp is turned off afterwards and kept such that the cathode is on the top.
Even in the case in which the experimental discharge lamp is designed for AC operation, the above described process for measuring the glow discharge voltage can be used since the observation is carried out only in the short time from after starting to immediately after the transition to the arc discharge.
As was described above, through this arrangement of the light source device, the restart properties are also improved in the instance of a hot restart, and furthermore, the discharge current of the discharge lamp (Ld) does not flow in the primary winding (Pe) and in the secondary winding (Se) of the high voltage transformer (Te) of the starter (Ue) until after starting the discharge of the discharge lamp (Ld), since the outside trigger method is used. Therefore no heat loss forms in the primary winding (Pe) and in the secondary winding (Se) of the high voltage transformer (Te) of the starter (Ue) therefore no heat loss forms. Thus a light source device can be implemented in which an increase in size and weight of the starter (Ue) is avoided.
Another embodiment of the invention is described below. As was described above, to shorten the time during which a restart is impossible it is a good idea to apply a no-load voltage, i.e., a high voltage, to the main discharge electrodes (E1, E2) as well to the apply the high voltage from the starter (Ue) to the auxiliary electrode (Et). This no-load voltage is a high voltage however need not always be a DC voltage. For example, only a brief AC high voltage is necessary in a feed device for AC operation.
For shortening the time during which restart is impossible, the time interval before formation of the high voltage at the starter (Ue) the high voltagexe2x80x94no-load voltage applied to the main discharge electrodes (E1, E2) is unimportant. In contrast, there is even the possibility that the danger of formation of an insulation breakdown in an unintended area is increased by the no-load voltage being a high voltage. Therefore the level of the dielectric resistance which is necessary for safety must be increased not only for the wire with the high voltage between the starter (Ue) and the auxiliary electrode (Et), but also for the wire between the feed device and the main discharge electrodes (E1, E2).
By increasing the no-load voltage applied to the main discharge electrodes (E1, E2) in a pulse-like manner, the time during which the high voltage is applied is shortened in the wire between the feed device and the main discharge electrodes (E1, E2). Therefore the danger of formation of an insulation breakdown in an unintended area can be reduced.
In the case in which the high voltage of the starter (Ue) is a DC voltage, after starting the starter (Ue), the no-load voltage can be increased in a pulse-like manner. In the case in which the high voltage of the starter (Ue) is pulse-like, it is necessary to synchronize the operation of the starter with the operation of the pulse-like increase of the no-load voltage and to reliably superimpose the two on one another during the interval the high voltage of the starter (e) and the pulse-like increase are formed.
By arranging the light source device according to one preferred embodiment of the invention, the hot restart properties are improved. Furthermore, a light source device can be implemented in which an increase in the size and weight of the starter (Ue) is avoided and in which the danger of an insulation breakdown in an unintended area is reduced.
The invention is described below according to another embodiment of the invention. As is shown in FIG. 3, when a high voltage is applied from one end of the secondary winding (Se) of the high voltage transformer (Te) of the starter (Ue) to the auxiliary electrode (Et) of the discharge lamp (Ld), between the inside of the discharge vessel (11) and the main discharge electrode (E1) on the side on which the other end of the secondary winding (Se) of the high voltage transformer (Te) is connected, a discharge path (Dp1) is formed and a dielectric barrier discharge produced.
However, between the inside of the discharge vessel (11) and the main discharge electrode (E2) on the side on which the other end of the secondary winding (Se) of the high voltage transformer (Te) is not connected, a discharge path (Dp2) is formed and a dielectric barrier discharge produced. The reason for this is the following:
A potential difference of at most roughly a few hundred V to 2 kV is applied to the electrodes (E1, E2). Since a voltage, for example, of roughly a few kV to a dozen or so kV is applied to the auxiliary electrode (Et), the potential difference between the electrodes (E1, E2) is sufficient for the main discharge.
Therefore an electrical charge is supplied by the dielectric barrier discharge to the main discharge electrode (E2) on the side on which the other end of the secondary winding (Se) of the high voltage transformer (Te) is not connected. Therefore it can be exposed to a high voltage by trying to prevent this electrical charge from breaking down. By exposure to a high voltage, a high voltage no-load voltage can be supplied to the two poles of the main discharge electrodes (E1, E2).
An especially simple arrangement of the feed device shown in FIG. 3 can prevent the electrical charge delivered by the dielectric barrier discharge from disappearing. Here the feed device is specifically arranged such that between the feed circuit (Bx) and the main discharge electrode (E2) on the side on which the other end of the secondary winding (Se) of the high voltage transformer (Te) is not connected, a diode (Dz) is inserted.
A high voltage pulse originates from the secondary winding (Se) of the high voltage transformer (Te). Thus, in the secondary winding of the transformer, essentially only one alternating current can form. By the inductance of the secondary winding (Se) and by a LC resonant circuit which is formed by the electrostatic capacity and the floating electrostatic capacity of the auxiliary electrode (Et) connected to it, a damping oscillation alternating high voltage is formed at the auxiliary electrode (Et).
During positive and negative phases with high absolute values of the voltage of the damping oscillation AC wave the above described dielectric barrier discharge is formed in each half period. In the case in which the auxiliary electrode (Et) is discharged during a negative phase, an attempt is made to negatively charge the main discharge electrode (E2) on the side on which the other end of the secondary winding (Se) of the high voltage transformer (Te) is not connected. In this case, the loaded electrical charge is neutralized because a current flows in the forward direction in the diode (Dz).
In the case in which the auxiliary electrode (Et) has been discharged during a positive phase, an attempt is made to positively charge the main charge electrode (E2) on the side on which the other end of the secondary winding (Se) of the high voltage transformer (Te) is not connected. But since in this case no current flows in the diode (Dz) through a reciprocal connection, the positively charged high voltage which is formed becomes a no-load voltage which is supplied to the main discharge electrodes (E1, E2). Therefore a main discharge can be induced between the electrodes (E1, E2) as the two poles, a dielectric barrier discharge is formed between the main discharge electrode (E1) on the side on which the other end of the secondary winding (Se) of the high voltage transformer (Te) is connected, which also continues after charging, on the inside of the discharge vessel (11).
In another embodiment, the hot restart property is also improved, and thus a light source device can be implemented in which an increase in size and weight of the starter is avoided, while keeping the arrangement for supplying a no-load voltage to the electrodes (E1, E2).
FIG. 3 shows an especially simple case. For a practical application it is however desirable to insert, for example, a protective component parallel to the electrodes (E1, E2), or parallel to the diode (Dz), with a resistance decreasing in the case of the application of a voltage which exceeds a given voltage, such as a varistor or the like, in order to prevent the diode (Dz) from being destroyed when the charging voltage of the electrode (E2) on the side to which the other end of the secondary winding (Se) of the high voltage transformer (Te) is not connected becomes too high.
A further embodiment of the invention is described below. The length of the current conduction path for connection of a circuit part on the secondary side of the high voltage transformer (Te) to the auxiliary electrode (Et) can be reduced by arranging the high voltage generating part (Ub) of the starter circuit, which comprises the high voltage transformer (Te), separately from the feed circuit part (By). In this way, the electrostatic capacity which is formed between the current conduction path connecting the circuit on the secondary side of the high voltage transformer (Te) to the auxiliary electrode (Et), and the conductor in the vicinity can be reduced. Furthermore the inductance of the current conduction path can be decreased. In the case in which the starter produces a pulsed high voltage, the negative effect is suppressed that the xe2x80x9cdulling distortionxe2x80x9d of the pulsed high voltage which is caused by the presence of the electrostatic capacity of the current conduction path and the presence of the inductance reduces the increase of the voltage between the electrodes. Furthermore, the disadvantage that greater energy than necessary must be delivered is likewise eliminated. Also, the possibility that the xe2x80x9cdulling distortionxe2x80x9d of the pulsed high voltage increases the pulse width and that in an unintended area an insulation breakdown is formed can be suppressed. Since the length of the current conduction path connecting the circuit part on the secondary side of the high voltage transformer (Te) to the auxiliary electrode (Et) can be reduced and thus the loop area can be made smaller, noise can be eliminated.
Because the length of the connecting wire between the starter and the auxiliary electrode (Et) is small, the possibility of the formation of an insulation breakdown can also be suppressed when the starter produces the high voltage during which the voltage increases relatively slowly.
For the high voltage transformer (Te) of the starter which produces a high voltage, its insulation efficiency is inevitably degraded by frequent use. On the other hand, the discharge lamp (Ld) has its limited service life. It must therefore be unconditionally replaced by a new discharge lamp after a limited time of use. Due to the integral arrangement of the discharge lamp (Ld) at least with the high voltage transformer (Te) of the starter, when the discharge lamp is replaced the high voltage transformer (Te) of the starter must also be replaced. Thus the danger of insulation breakdown as a result of degradation of the insulation efficiency of the high voltage transformer (Te) of the starter can be prevented.
Furthermore, there are the advantages that the possibility of formation of an insulation breakdown in an unintended area is reduced and that the disadvantage of noise is also reduced in the case in which the starter produces a pulsed high voltage by the measure that the length of the connecting line between the starter and the auxiliary electrode (Et) is reduced even more. In this case, the integral arrangement with an optical means for controlling emissions from the discharge lamp (Ld) in a certain direction, such as a concave reflector or the like, simplifies the interchangeability of the discharge lamp.
The arrangement of the light source device according to this development of the invention improves hot restart properties, and a light source device can be implemented in which an increase in size and weight of the starter (Ue) is avoided, and in which the danger of an insulation breakdown in an unintended area is greatly reduced, and noise is reduced.
The invention is further described below using several embodiments shown in the drawings.